kdurg

I am running 225/40/18 in the front....and while I am very pleased with the "look" of the 285's in the rear....the fronts appear to be too "skinny" .

Is anyone running something a bit thicker in the front.....? Say a 235 or 245?? and what would be the corresponding aspect ratio for that width?
35 or 30 ?

Any rubbing issues in the front considering it is dropped with RoW M030's?

Thanks in advance for the input and expertise !!!!

Keith

Jeff 993TT

you can run bigger rubber in the front, but you have to be aware of serveral things:

a) bigger front tires mean more tramlining while driving in ruts on the street
b) bigger front tires mean steering is harder
c) bigger front tires mean more grip up front ==> less understeer
d) bigger front tires mean the ratio between the rears are different now, chnages the load characteristic on the viscous coupling ( ie front vs rear power delivery )
e) bigger front tires mean less clearance in the wheel well ( may require shocks with smaller diameter springs, may require special camber settings and camber plates, may requre fender rolling/cutting )

With all that said, why do you want to increase just your front tire size? I think a nicely balanced car with good suspension and sway bars is a better path. A nicely balanced car is more important that the "look", imho.

When I needed to get new tires, I too thought that I could get less understeer by just replacing the front tires, but it was my pitiful sway bars that were making my car understeer. The 225/285 balance is pretty good for most driving that people do.

There are a few other lunatics out there, aka viper bob, who runs 245/315's on his car... I think... But he has cut away part of this rear fender, has Motons, has monoballs, and custom offset wheels.

ca993twin

Keith,

An interesting research topic. While rubbing is not the concern (should be fine with either of those sizes), the AWD needs a fairly close match between the rolling circumference of the fronts and the rear. Here's where it gets tricky; every tire manufacturer specs their tires a little differently... even with the same tire size. If you look at tirerack,.com, you can find the specifications for various manufacturers for the "revs/mile" for all of their tires. You'll need to determine which size will more closely match the rear revs/mile.

Some small difference between front and read is OK (I don't know that number... maybe someone else can jump in). When my tires wear out, I'll be doing the same research, but with wider tires on both front and rear (I now have 295x30x18 rear).

Phil

I have 265's up front!

kdurg

Great input guys....I really appreciate you taking the time to respond !!

I've got more research to do....clearly.

KD

JohnM

245/35 fronts are a pretty much perfect rolling diameter match to 285/30 rears. Fitting them will indeed reduce understeer (that's why I went for the 245/285 combination). In the case of Pzero Rosso (one of the few brands that offers these sizes) the 245/35 front is also softer (TW 160 vs 220 for 225/40 and 285/30) hence (presumably) even more grip, and a slightly more even front/rear wear balance. There was no change in steering effort, grip is good, clearance is not a problem. The 245 tyre is a fairly tight fit on the 8x18 wheel (i.e. the tyre fitter will have some fun with it) but it looks perfect when on, same appearance as the 285 rear on the stock 10x18.

If you are not comfortable with changes in your car's handling balance, stick with the 225/285 combination.

Michael Ghia

Didn't Porsche actually fit tyres with different O/D's (front to rear) to make the VP transfer 5-15% of drive to the front wheels at all times?
I know that the 964 system is very different to the 993.
Anyone?
Does anyone have stock sizes written down for the 993 C4?
Cheers
Mike Ghia

swmic

Keith,

I went with 235/40/18 and 275/35/18 front and back. The difference in the circumference is only 0.5%. I have a C4 with the ROW M030 springs so matching the revs/mile and clearance was an issue for me also.

Shawn